The spectral and covariance properties of surface-scattered acoustic fields are determined for slightly rough and very rough sea surfaces that are irradiated with far-field, single frequency sources. The results obtained are general in the sense that they depend only on the frequency-wavenumber spectrum of the stochastic sea surface and not on any particular surface spectrum. Exact results are obtained for sinusoidal seas and these results are compared with various approximate solutions. The approximations clearly indicate the connection between sinusoidal seas. (Author).

This book provides an up-to-date introduction to the theory of sound propagation in the ocean. The text treats both ray and wave propagation and pays considerable attention to stochastic problems such as the scattering of sound at rough surfaces and random inhomogeneities. An introductory chapter that discusses the basic experimental data complements the following theoretical chapters. New material has been added throughout for this third edition. New topics covered include: - inter-thermocline lenses and their effect on sound fields - weakly divergent bundles of rays - ocean acoustic tomography - coupled modes - sound scattering by anisotropic volume inhomogeneities with fractal spectra - Voronovich's approach to sound scattering from the rough sea surface. In addition, the list of references has been brought up to date and the latest experimental data have been included.

As man turns his attention from the overcrowded continents of this planet and explores the spaciousness of the ocean, the applications of ocean acoustics become increasingly numerous and important. This book pro- vides an up-to-date introduction to the theory of sound propagation in the ocean, with much new material having been added throughout the second edition. It includes both ray and wave treatments and considerable attention is paid to stochastic problems such as the scattering of sound at rough surfaces and random inhomogeneties. An introductory chapter that discusses the basic experimental data complements the following theoretical chapters.

In this book, key discoveries in the field of statistical ocean acoustics over the last 35 years are addressed with illustrations from ocean observations.

This report is a collection of three papers on two subjects: the scattering of acoustic waves from rough surfaces and the time variation of ambient sea noise. Part I, on scattering, treats the stochastic character of a plane-wave signal that has been reradiated from a rough surface, through an investigation of the properties of the coherence of the reradiation. Parts II and III, on noise, describe the results thus far obtained in an experimental program to investigate the time variation of low-frequency ambient sea noise. (Author).

Analytic methods are used to assess the impact of the two-dimensional (2-D) wave spectrum of a wind-driven sea on multistatic low-frequency surface reverberation. The problem is initially posed with a narrowband source beneath a time-dependent sea surface in an ocean that can have depth dependence and bottom layering. The propagated signal interacts with the slower moving surface waves to produce a narrowband scattered field. The small-waveheight approximation is applied to a deterministic sea surface to express the scattered field in terms of the surface elevation and the Green's function for a perfectly calm sea. Randomness is then incorporated into the surface description, and its impact is formulated for an arbitrarily placed pair of receivers. The three-dimensional (3-D) cross-spectral density (CSD) of the reverberation is reduced to a sum of baseband and sideband terms formulated as multiple mean-sea-surface integrals. The sideband result is identified as an active scattering generalization of the van Cittert-Zernike theorem from partial coherence theory. The focus is then narrowed to shallow deployment in a homogeneous ocean, and stationary-phase estimates are used to produce analytic expressions for the CSD. The zero-Doppler component and Bragg-Doppler sidebands are expressed in terms of the power spectrum of the source, the power spectrum and directionality of the surface waves, and the multistatic source/receiver geometry. Sample sideband calculations are provided to illustrate the results, and system implications are considered.

The ocean is opaque to electromagnetic radiation and transparent to low frequency sound, so acoustical methodologies are an important tool for sensing the undersea world. Stochastic sound-speed fluctuations in the ocean, such as those caused by internal waves, result in a progressive randomisation of acoustic signals as they traverse the ocean environment. This signal randomisation imposes a limit to the effectiveness of ocean acoustic remote sensing, navigation and communication. Sound Propagation through the Stochastic Ocean provides a comprehensive treatment of developments in the field of statistical ocean acoustics over the last 35 years. This will be of fundamental interest to oceanographers, marine biologists, geophysicists, engineers, applied mathematicians, and physicists. Key discoveries in topics such as internal waves, ray chaos, Feynman path integrals, and mode transport theory are addressed with illustrations from ocean observations. The topics are presented at an approachable level for advanced students and seasoned researchers alike.